Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define all(vec) vec.begin(),vec.end()
using ll=long long;
const ll MOD=1e9+7;
const int INF=1<<30;
const int dy[4]={0,0,1,-1};
const int dx[4]={1,-1,0,0};

int hosuu[50][50];

int main(){
  int H,W; cin >> H >> W;
  vector<string> G(H);
  rep(i,H){
    cin >> G[i];
  }
  queue<pair<int,int> > que;
  que.push(make_pair(0,0));
  while(!que.empty()){
    int y,x;
    tie(y,x)=que.front();
    que.pop();
    rep(dir,4){
      int ny=y+dy[dir];
      int nx=x+dx[dir];
      if(0<=ny&&ny<H&&0<=nx&&nx<W&&G[ny][nx]=='.'&&hosuu[ny][nx]==0){
        hosuu[ny][nx]=hosuu[y][x]+1;
        que.push(make_pair(ny,nx));
      }
    }
  }
  int sum=0;
  rep(i,H){
    rep(j,W){
      if(G[i][j]=='#'){
        sum++;
      }
    }
  }
  if(hosuu[H-1][W-1]>0) cout << H*W-(sum+hosuu[H-1][W-1]+1) << endl;
  else cout << -1 << endl;
}